A mining method for deep thin tungsten ore veins suitable for complex void group conditions

Abstract

The present application relates to a method for mining thin tungsten ore veins in deep areas under complex void group conditions, which includes the following steps: S1. Divide the mine into three sections and construct a bulk isolation layer in the upper middle section; S2. Arrange rock drilling layered tunnels, cutting shafts, cutting cross tunnels, and cutting grooves to form compensation space for the first free blasting of the mine; S3. Drill rock in the mine cutting cross tunnels and blast to form transverse cutting vertical grooves; S4. Drill upward fan-shaped medium-deep holes in the layered tunnels, blasting with the cutting grooves as the free surface for the first blasting, and ensure that the upper layer is 1 to 2 rows ahead of the lower layer in the second and subsequent blastings, forming a stepped extrusion blasting and ore collapse; S5. Load the ore into the mine car and transport it to the concentrator for processing. The present application utilizes the reconstructed bulk isolation layer under the void group to effectively separate the upper void from the mining middle section, thereby ensuring the safety of ore recovery under the void group, and efficiently recovering ore, improving the ore recovery rate, reducing the cost of ore mining, and improving the economic benefits of the mining enterprise.

Description

Technical Field

[0001] The present application relates to the technical field of ore mining methods, and in particular to a deep thin tungsten ore vein mining method suitable for use under complex void group conditions. Background Art

[0002] Influenced by hydrothermal vein-type deposits, wolframite deposits mostly occur in vein-like forms. Steeply dipping fine vein clusters are a major characteristic of tungsten deposits, with numerous parallel complex veins forming vein groups. Based on engineering geological conditions, the shallow hole ore-retention method is considered the most effective. After decades of mining, numerous parallel voids have formed in the upper portions of most mines. As mining continues, the mining environment and geological conditions, such as mining stress, dense veins, and structural development, have gradually increased the difficulty of mining. This has significantly limited the recovery rate of deep-lying resources, which is mainly reflected in the following three aspects.

[0003] First, as mining extends to deeper areas, under the influence of mining stress and void penetration, the stability of the vein group voids formed by the upper shallow hole ore retention method further decreases, and the walls between the voids are extremely prone to collapse, causing the scale of the voids to expand and then trigger strong ground pressure activities, posing a huge safety hazard to deep ore mining.

[0004] Secondly, the deep veins are becoming thicker and the spacing between vein groups is becoming smaller. If the traditional shallow hole ore retention method is continued to be used, the rock mass between the veins will be difficult to ensure self-stability, and it will be necessary to rely on losing the veins to increase the thickness of the mining area wall, thereby significantly reducing the resource recovery rate.

[0005] Third, under the combined effects of complex empty areas above and high-stress mining in deep areas, the original shallow-hole ore-retention method continues to be used for mining. The labor intensity of workers has not been reduced, and the safety risks of working directly under the roof have been further increased, affecting the safe recovery of resources.

[0006] Due to the aforementioned major technical difficulties, the current resource recovery rate for deep, fine-vein tungsten deposits using the shallow-hole ore-leaving method is only 40% to 50%. Furthermore, the deteriorating mining environment has increased labor safety hazards, resulting in a 20% increase in stope operation and support costs. All of these factors have led to a continuous decline in the economic benefits of tungsten mining companies. Therefore, for the mining of fine-vein tungsten deposits located beneath complex goaf clusters, the conventional shallow-hole ore-leaving method has serious drawbacks in terms of safety and efficiency. In the absence of a ready-made set of technologies and experience available for reference at home and abroad, new methods must be introduced to address this issue. Summary of the Invention

[0007] In order to improve the problems of low mining efficiency, low mining safety and high mining cost in deep thin-vein tungsten deposits, the present application provides a deep thin-vein tungsten ore mining method suitable for complex void group conditions.

[0008] The present application provides a method for mining deep thin tungsten ore veins under complex void group conditions, which adopts the following technical solutions:

[0009] A method for mining deep thin tungsten ore veins under complex void group conditions, comprising the following steps:

[0010] S1. Divide the mine into three sections, each 12-13m high, and construct a bulkhead insulation layer at the same location in the upper middle section. The bulkhead insulation layer is at least 20m thick.

[0011] S2. Excavate a connecting shaft tunnel between the intermediate pillars and the transport tunnel in the footwall of the vein. Arrange a pedestrian equipment shaft and excavate a connecting drilling tunnel and a layered drilling tunnel. The layered tunnel communicates with the connecting drilling tunnel on the other side of the mine. Arrange a cutting shaft at one end of the mine, connecting with the upper and middle transport tunnels. Arrange a cutting tunnel from the layered tunnel corresponding to the cutting shaft. Cutting grooves are formed between the cutting shaft and the cutting tunnel using medium-deep holes to create compensation space for the first free blast in the mine.

[0012] S3. Drilling in the mine's cut-out lanes, using the cutout shaft as the blasting free surface, and forming transverse cutouts using upward parallel medium-long holes or fan-shaped medium-long holes;

[0013] S4. Drill upward fan-shaped medium-deep holes in the layered drift and charge them. The first blast is conducted using the cut groove as the free surface. For the second and subsequent blasts, ensure that the upper layer is 1-2 rows ahead of the lower layer, forming a stepped extrusion blasting and ore collapse.

[0014] S5. After the mine room is squeezed and blasted, it is ventilated and the blasting smoke is blown away. After passing the security inspection, the ore is raked with an electric rake in the electric rake road and raked into the short-term ore retention shaft. The ore is loaded into the mine car through the ore discharge gate arranged in the vein tunnel, and then the locomotive pulls the mine car to the concentrator for processing.

[0015] Furthermore, before constructing the dispersed isolation layer in step S1, the position selection analysis of the dispersed isolation layer is first carried out, and four ore body models with different inclinations of 0°, 15°, 45°, and 75° are established; in each of the ore body models, the dip extension length of the goaf is set to 300m, the goaf length is 50m long for a single mining area, and is divided into 6 middle sections. The thickness of the goaf is set to 5m based on the thickness of two or more thin veins, and each type of inclination model has dispersed isolation layers at different positions along the inclination direction.

[0016] Furthermore, 5 of the 6 middle sections are selected as analysis positions of the bulk isolation layer, and the deformation energy released during the excavation process is compared and analyzed. The analysis position corresponding to the minimum deformation energy is the selected position of the bulk isolation layer.

[0017] Furthermore, the thickness of the dispersed isolation layer constructed in step S1 is calculated as follows:

[0018] ;

[0019] Where:

[0020] ——Thickness of effective bulk insulation layer, in m;

[0021] — roughness coefficient, ; is the average diameter of the falling rock blocks, in m;

[0022] ——height of rock stratum collapse, in m;

[0023] ——Thickness of rock layer that may collapse, in m;

[0024] ——The ratio of the falling area, that is, the ratio of the falling area to the exposed area.

[0025] Furthermore, when constructing the dispersed isolation layer in step S1, shallow holes, medium-deep holes and deep holes are coordinated to drill rocks and charge explosives at corresponding positions in the mining area, and small goafs are used as blasting compensation spaces. The dispersed isolation layer is formed by one-time blasting or segmented blasting.

[0026] Furthermore, the detonation method for constructing the said bulk isolation layer adopts a double detonation network of detonating tubes and detonating cords, and micro-difference blasting of detonating tube detonators. The blasting sequence is: shallow hole blasting of peach-shaped bottom pillars in the construction area mining area - medium and deep hole blasting of partition walls in the construction area - deep hole blasting of surrounding rocks in the construction area.

[0027] Furthermore, during the entire mining and cutting construction process, mechanical forced ventilation is used, and fresh air flows into the mining working face from the lower plate along the vein transport tunnel, pedestrian equipment shaft, and layered horizontal tunnel; the blasting smoke is discharged from the gaps in the ore pile, flows back to the upper and middle sections of the return air tunnel, and then discharged to the return air shaft.

[0028] Furthermore, before blasting in step S4, stress gauges or wooden slides or other ground pressure observation means are arranged in the rock of the stope surrounding rock and the rock of the pillar tunnel to monitor the ground pressure in the mining area to guide safe mining in the stope.

[0029] Furthermore, after each blast in step S4, the ore output is controlled at 30-40% of the collapsed ore volume, providing compensation space for the next mine room compression collapse; after all the ore in the mine room has collapsed, the ore is evenly discharged at one time.

[0030] Furthermore, when mining in the stope, the sections with large, concentrated and complex stress in the same middle section are mined first, and the sections with small stress are mined later; between the middle sections, the upper middle section is mined first, and the lower middle section is mined later.

[0031] In summary, the beneficial technical effects of this application are:

[0032] 1. The reconstructed bulk isolation layer under the goaf group is used as a stress isolation zone to effectively separate the upper goaf from the mining middle section, ensuring the safety of ore recovery under the goaf group;

[0033] 2. This project has developed a high-efficiency mining technology for parallel thin tungsten deposits beneath a bulk isolation layer. Compared to the existing shallow hole ore retention method, this high-efficiency mining technology can increase the recovery rate of parallel thin vein deposits by 45%, allowing for the safe mining of deep thin tungsten deposits and avoiding resource waste.

[0034] 3. The implementation of safe and efficient mining technology for thin vein tungsten deposits under complex void groups avoids concentrated exposure of workers under the roof, significantly reduces the mining accident rate, improves workers' labor efficiency, reduces workers' labor intensity, and efficiently recovers ore, increases ore recovery rate, reduces ore mining costs, and improves the economic benefits of mining enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of controlling multiple mid-section ground pressures using a dispersed isolation layer in an embodiment of the present application;

[0036] Figure 2 is a cross-sectional view of the stage of segmented rock drilling in an embodiment of the present application;

[0037] Figure 3 It is along Figure 2 Schematic diagram of the cross-sectional structure along line AA.

[0038] Description of reference numerals:

[0039] 1. Intermediate pillars; 2. Bulk isolation layer; 3. Partition; 4. Cutting groove; 5. Short-term ore-drawing shaft; 6. Funnel; 7. Medium-deep hole; 8. Layered horizontal tunnel; 9. Pedestrian equipment shaft; 10. Rock drilling connecting tunnel; 11. Electric rake road; 12. Footwall along-vein transport tunnel. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solution of this application in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0041] The complex mining environment of fine-vein tungsten ore is mainly reflected in three aspects: First, after years of mining activities, a large number of untreated goafs and interlayer rock bodies have been formed in the upper part of the mine. The spans of the goafs and the thicknesses of the interlayer rock bodies vary greatly, the number is large, and the goaf groups are extremely complex; second, under the combined influence of mining disturbances and ground stress, the interlayer rock bodies between the goafs are difficult to maintain long-term stability. Due to the lack of effective surrounding rock control technology, the subsequent mining of the upper plate and roof rock bodies frequently experience collapse and roof caving, and even a domino effect of goaf group collapse occurs; third, as mining extends to deeper areas, the complex mining environment in the upper part seriously threatens the safe recovery of deep resources in the mining area.

[0042] In addition, due to the influence of mining methods and mining costs, as well as the complexity of the void group, it is unlikely to completely fill the complex void group formed above.

[0043] This application addresses this situation through theoretical analysis, numerical simulation, and technological research and development. The application aims to understand the structural stability control laws of complex void clusters, achieve mechanical separation between the upper void cluster and the lower mining area, and develop a mining environment reconstruction technology for fine-vein tungsten deposits in complex environments. This technology provides technical support and safety assurance for the safe recovery of resources beneath the void clusters. The details are as follows.

[0044] The present application discloses a method for mining deep thin tungsten ore veins under complex void group conditions. Figure 1 、 Figure 2 and Figure 3 , which includes the following steps:

[0045] S1. Divide the mine room into three sections, each section is 12 to 13 meters high, and build a bulk isolation layer 2 at the same position in the upper middle section. The bulk isolation layer 2 is at least 20 meters thick. Its purpose is to prevent the upper ground pressure from affecting the lower mining and ensure the safety of the lower operation.

[0046] S2. Excavate a connecting shaft tunnel between the center of pillar 1 and the transport tunnel at the foot of the vein. Arrange a pedestrian equipment shaft (or a small bucket plus pedestrian equipment shaft 9). Excavate a rock drilling tunnel 10 and a rock drilling level tunnel 8 from the pedestrian equipment shaft 9 toward the mine room. The level tunnel 8 connects to the rock drilling tunnel 10 on the other side of the mine room. Excavate an electric rake connecting tunnel and electric rake track 11 from the pedestrian equipment shaft 9, 3m above the transport tunnel, toward pillar 1. The spacing between the funnels 6 is 7m, and the funnel neck and bucket diameter are 2.0×2.0m. 2 A cutting shaft is arranged at one end of the mine room, which is connected with the upper middle transport level tunnel. A cutting cross tunnel is arranged from the layered level tunnel 8 corresponding to the position of the cutting shaft. The cutting shaft and the cutting cross tunnel form a cutting groove 4 with a medium-deep hole 7 to form a compensation space for the first free blasting of the mine room.

[0047] S3. Drilling in the mine room cutting horizontal tunnel, with the cutting shaft as the blasting free surface, using the upper parallel deep hole 7 or fan-shaped deep hole 7 blasting to form a horizontal cutting vertical groove, or, the cutting vertical groove can also be formed by the small mining method.

[0048] S4. Drill upward fan-shaped medium-deep holes 7 in the layered level tunnel 8 and charge them. The first blasting is carried out with the cutting groove 4 as the free surface. In the second and subsequent blasting, ensure that the upper layer is 1 to 2 rows ahead of the lower layer, forming a stepped extrusion blasting and ore collapse.

[0049] S5. After the mine room is squeezed and blasted, it is ventilated and the blasting smoke is blown away. After passing the security inspection, the ore is raked with an electric rake in the electric rake road 11 and raked into the ore short retention shaft 5. The ore is loaded into the mine car through the ore discharge gate arranged in the vein roadway, and then the locomotive pulls the mine car to the concentrator for processing.

[0050] Before constructing the bulkhead isolation layer 2 in step S1, the location of the bulkhead isolation layer 2 is first analyzed. By combining the effects of the secondary stress field during the mining process, the correlation between the bulkhead isolation layer 2 and the goaf inclination angle can be determined through numerical simulation. Specifically, orebody models with four different inclination angles of 0°, 15°, 45°, and 75° are established. To simplify the calculation process, the goaf size is combined with the occurrence of thin vein groups. In each orebody model, the goaf's dip extension length is set at 300m (planned to be divided into six sections from +150m to -150m), and the goaf length is 50m, the length of a single stope. The goaf thickness is determined to be 5m, taking into account the thickness of two or more thin veins. For each inclination model, the bulkhead isolation layer 2 is positioned at different locations along the inclination direction.

[0051] In order to simplify the calculation, the assumption of small deformation of elastic body is adopted. According to Saint-Venant principle, when building the model, the units of the surrounding rock part far away from the ore body are divided into larger areas, and the ore body units are divided more densely. Each unit is divided into the same size area to facilitate calculation. The overall model is divided into 137680 units and 156444 nodes. The mechanical parameters of the rock mass are selected from the mechanical parameters of the main surrounding rock metamorphic sandstone of Gannan Tungsten Mine. The corresponding bulk density, elastic modulus and Poisson's ratio are respectively =2.7t / m3, =16740MPa, =0.09, and the acceleration of gravity is 10m / s2. The constraints are selected as follows: the bottom is constrained in the z direction, and the two sides are constrained in the x and y directions respectively. A load is also applied to the upper part of the ore body model to simulate the deadweight of the surrounding rock above the void.

[0052] The lower left corner of the model is selected as the coordinate origin, the horizontal right direction is the positive x direction, the horizontal backward direction is the y direction, and the vertical upward direction is the z direction. Calculations are performed in this coordinate system. The specific calculation process is divided into five cases for comparative analysis. Specifically, five of the six middle sections are selected as the analysis positions of the dispersed isolation layer, corresponding to the isolation layer positions of 100-120m, 50-70m, 0-20m, -50--30m, and -100--80m, respectively. The deformation energy released during the excavation process is compared and analyzed through the above five cases, and the analysis position corresponding to the minimum deformation energy is the selected position of the dispersed isolation layer 2.

[0053] According to analysis, the optimal support point for voids formed by horizontal ore bodies is located in the middle of the void. As the ore body's inclination increases, the optimal position of the bulk isolation layer 2 shifts from the middle of the void toward the lower portion. When the ore body becomes steeply inclined, the optimal support position for the void formed after mining is located at the lower portion. Calculations of the combined deformation energy and its ratio show that the magnitude of the shift in the optimal position of bulk isolation layer 2 decreases as the void changes from inclined to steeply inclined (concentrating in the lower and middle portions), but it still provides critical support for the void. Therefore, for mining ore bodies beneath steeply inclined thin vein clusters, bulk isolation layer 2 should be located at the lower portion of the void cluster. Implementing bulk waste rock filling or blasting the surrounding rock to a certain height below the void to form a built-up bulk isolation layer 2 effectively controls the displacement of the upper and lower walls, mitigates the shock waves generated by void instability, and is suitable for the practical engineering practice of thin vein open-field mining in tungsten mines.

[0054] Therefore, by constructing an ore body model for analysis and calculation, the location for setting up the bulk isolation layer 2 with the smallest overall deformation performance and the best supporting effect can be selected. The key middle section area can be selected along the inclined extension direction of the ore body to construct a stress isolation zone, and the upper void area can be effectively divided. Under the support of the isolation layer, the subsequent overall deformation energy of the upper and lower parts of the void area can be minimized, thereby achieving effective control of the overall ground pressure activity in the void area, and also effectively controlling the structural cost and the control effect of the overall ground pressure activity in the void area.

[0055] Furthermore, during specific mining, the thickness of the bulk isolation layer 2 constructed in step S1 is calculated as follows:

[0056] ;

[0057] Where:

[0058] ——Thickness of effective bulk insulation layer 2, in m;

[0059] — roughness coefficient, ; is the average diameter of the falling rock blocks, in m;

[0060] ——height of rock stratum collapse, in m;

[0061] ——Thickness of rock layer that may collapse, in m;

[0062] ——The ratio of the falling area, that is, the ratio of the falling area to the exposed area.

[0063] Therefore, by calculating the effective thickness of the dispersed isolation layer 2, the construction of the dispersed isolation layer 2 can be effectively controlled to ensure that the dispersed isolation layer 2 exerts the maximum effect.

[0064] In addition, when constructing the bulk isolation layer 2 in step S1, shallow holes, medium-deep holes 7, and deep holes are coordinated to drill rocks and charge explosives at corresponding positions in the mining area, and small goaf areas are used as blasting compensation spaces. The compensation coefficient is controlled at more than 21%, and the bulk isolation layer 2 is formed by one-time blasting or segmented blasting.

[0065] During the specific operation, the depth of the blasthole is different when drilling at different positions. Generally, three types of blastholes are used: Φ42mm, Φ60mm, and Φ100mm.

[0066] (1) Shallow hole: The hole diameter is Φ42mm and the length is 1 to 2m. The rock drilling machine is YSP-45 pneumatic rock drill. The rock drilling site is in the peach-shaped ore pillar of the shallow hole ore retention method stope. The explosive is 2# rock emulsion explosive roll.

[0067] (2) Medium-deep holes: The hole diameter is Φ60mm and the length is 5 to 15m. The rock drilling adopts the YGZ90 type rail-type independent rotary rock drill. The rock drilling site is the wall between the parallel stopes of the shallow hole ore retention method. The explosive is porous granular viscous ammonium nitrate explosive.

[0068] (3) Deep hole: The hole diameter is Φ100mm and the length is 15 to 30m. The drilling is carried out using a KQJ-100B down-the-hole drill rig. The drilling site is in the upper and lower surrounding rocks of the shallow hole ore-retention method stope. The explosive is porous granular viscous ammonium nitrate explosive.

[0069] The detonation method utilizes a composite detonating tube and detonating cord detonator network, with micro-difference blasting of the detonating tube detonators. The specific detonation method involves inserting a single detonating tube millisecond detonator and a single detonating cord into the hole. A branch detonating cord is then connected to each detonating cord inside the hole. A detonating tube detonator from the same section as the one inside the hole is then tied to each end of the branch detonating cord for detonation. The hole detonating tubes are evenly tied around the main detonating cord. A DBG-2 detonating tube trigger activates and detonates two parallel 20-minute long-delay detonators, transmitting the detonation with dual detonating cords. The blasting sequence is: shallow hole blasting of the peach-shaped bottom pillar in the construction area, medium-deep hole blasting of the partition wall in the construction area, and deep hole blasting of the surrounding rock in the construction area.

[0070] In addition, in step S2, referring to Figure 2and Figure 3 In a mining example, the cross section of the skylight connecting tunnel is 2.0×2.3m 2 , pedestrian equipment well 9 section 1.8×3.5m 2 , rock drilling connecting tunnel 10 section 2.5×2.5m 2 , rock drilling layered level tunnel 8 sections 2.5×2.5m 2 , electric rake road 11 section 2.0×2.2m 2 , cutting the skylight section 1.8×3.0m 2 , cutting cross-tunnel section 2.5×3.0m 2 .

[0071] Moreover, in step S3, after the vertical groove is formed, a YGZ-90 drill is used to drill upward fan-shaped medium-deep holes in the layered level tunnel 8, with a hole diameter of Φ60 mm, a row spacing of 1.2 m, and a hole bottom distance of 2.2 m. Porous granular viscous ammonium nitrate explosive is used for blasting, and the explosives are charged using a BQF-100 pneumatic charger. The explosives are detonated using non-electric initiation methods such as explosive packs, millisecond difference detonators for detonating tubes, detonating cords, and detonating tubes. A DBG-2 detonating tube trigger is used to trigger and detonate two long-delay detonating tube detonators for 20 minutes (or four in parallel or in series for 40 minutes).

[0072] Blasting of the bulk isolation layer 2 in the upper middle section can be carried out simultaneously with the first free blasting of the mine chamber. The second and subsequent blasting of the mine chamber is compression blasting. To prevent the blasting seismic and shock waves from the blasting from affecting the ore pillars, the electric rake road 11, and the facilities within the pedestrian equipment shaft 9, the number of rows of blasting should be controlled. Each layer can be arranged with 3 to 5 rows, and the detonator sections of each row are different, and the same section is the same within the same row. The upper and lower layers can be collapsed synchronously. Generally, the upper layer will lead the lower layer by 1 to 2 rows of holes, forming a "staircase" shape. Because the mine chamber is subjected to compression blasting, the working surfaces at the ends of each layer can also be straight, not ahead, to facilitate loosening and ore drawing.

[0073] Furthermore, mechanical forced ventilation must be maintained throughout the entire mining and cutting process, and ventilation safety management must be strengthened. During chambered mining, since the three strata of the caving method are formed by collapsed ore piles at their ends, fresh air enters the stope working face from the footwall along-the-vein transport tunnel 12, the pedestrian equipment shaft 9, and the stratified level tunnel 8. Blasting smoke is discharged through gaps in the ore pile, flowing back into the upper and middle return air tunnels and then to the return air shaft. The ore pile has high wind resistance and poor ventilation, requiring extended ventilation time.

[0074] To better control ground pressure, in addition to selecting an appropriate mining method, a reasonable mining sequence must be used to arrange the ore blocks. Specifically, when mining in the stope, the sections with high, concentrated, and complex stresses are mined first, followed by sections with low stresses. Between sections, the upper section is mined first, followed by the lower section. Furthermore, after each blast in step S4, the ore output is controlled at 30-40% of the collapsed ore volume. This is to loosen the ore pile at the working face and provide compensation space for the next mine collapse. After all the ore in the mine has collapsed, the ore is evenly discharged all at once.

[0075] And because the present application mines the ore blocks back and forth by extrusion blasting, a portion of the ore needs to be released after each collapse to loosen the ore pile and provide compensation space for the next extrusion blasting. Since there is no goaf after the mine room blasting, the stress in the mining area is released, and the ore pile supports the upper and lower surrounding rocks. The main form of the mining area ground pressure is the impact ground pressure caused by the bottom structure of the ore block such as the electric rake road 11, the roof of the lower plate along the vein transport tunnel 12 sinking and spalling, and the collapse of the upper middle section of the bulk isolation layer 2. Therefore, before blasting in step S4, stress observation means such as stress gauges or wooden slides should be arranged in the rock of the mining area surrounding rock and the pillar tunnel to monitor the ground pressure in the mining area to guide the safe mining of the mining area.

[0076] Unless otherwise defined, the technical or scientific terms used in this application shall have the usual meanings understood by persons of ordinary skill in the field to which this application belongs. The words "first", "second", "third" and similar terms used in the specification and claims of this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "one" or "a" do not indicate a quantity limitation, but rather indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before "include" or "comprises" cover the elements or objects listed after "include" or "comprises" and their equivalents, and do not exclude other elements or objects. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0077] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for mining deep thin tungsten ore veins under complex void group conditions, characterized in that: The following steps are involved: S1. Divide the mine into three sections, each 12-13m high, and construct a bulkhead insulation layer at the same location in the upper middle section. The bulkhead insulation layer is at least 20m thick. S2. Excavate a connecting shaft tunnel between the intermediate pillars and the transport tunnel in the footwall of the vein. Arrange a pedestrian equipment shaft and excavate a connecting drilling tunnel and a layered drilling tunnel. The layered tunnel communicates with the connecting drilling tunnel on the other side of the mine. Arrange a cutting shaft at one end of the mine, connecting with the upper and middle transport tunnels. Arrange a cutting tunnel from the layered tunnel corresponding to the cutting shaft. Cutting grooves are formed between the cutting shaft and the cutting tunnel using medium-deep holes to create compensation space for the first free blast in the mine. S3. Drilling in the mine's cut-out lanes, using the cutout shaft as the blasting free surface, and forming transverse cutouts using upward parallel medium-long holes or fan-shaped medium-long holes; S4. Drill upward fan-shaped medium-deep holes in the layered drift and charge them. The first blast is conducted using the cut groove as the free surface. For the second and subsequent blasts, ensure that the upper layer is 1-2 rows ahead of the lower layer, forming a stepped extrusion blasting and ore collapse. S5. After the mine room is squeezed and blasted, ventilation is carried out to disperse the blasting smoke. After passing the safety inspection, the ore is raked with electric rakes in the electric rake road and raked into the short-term ore retention shaft. The ore is then loaded into the ore car through the ore discharge gate arranged in the vein roadway. The ore car is then pulled by a locomotive and transported to the concentrator for processing. Before constructing the bulk isolation layer in step S1, a bulk isolation layer position selection analysis is first performed to establish ore body models with four different inclination angles of 0°, 15°, 45°, and 75°; in each ore body model, the goaf dip extension length is set to 300m, the goaf length is 50m long for a single stope, and is divided into 6 middle sections; the goaf thickness is set to 5m based on the thickness of two or more thin veins; and bulk isolation layers are set at different positions along the inclination direction for each type of inclination model; And 5 of the 6 middle sections are selected as the analysis positions of the dispersed isolation layer, and the deformation energy released during the excavation process is compared and analyzed. The analysis position corresponding to the minimum deformation energy is the selected position of the dispersed isolation layer.

2. The method for mining deep thin tungsten ore under complex void group conditions according to claim 1 is characterized in that: The thickness of the dispersed isolation layer constructed in step S1 is calculated as follows: ； Where: ——Thickness of effective bulk insulation layer, in m; — roughness coefficient, ; is the average diameter of the falling rock blocks, in m; ——height of rock stratum collapse, in m; ——Thickness of rock layer that may collapse, in m; ——The ratio of the falling area, that is, the ratio of the falling area to the exposed area.

3. The method for mining deep thin tungsten ore under complex void group conditions according to claim 1 is characterized in that: When constructing the bulk isolation layer in step S1, shallow holes, medium-deep holes and deep holes are coordinated to drill rocks and charge explosives at corresponding positions in the stope, and small goafs are used as blasting compensation spaces. The bulk isolation layer is formed by single blasting or segmented blasting.

4. The method for mining deep thin tungsten ore under complex void group conditions according to claim 3 is characterized in that: The detonation method for constructing the bulk isolation layer adopts a composite detonation network of detonating tubes and detonating cords, and micro-difference blasting of detonating tube detonators. The blasting sequence is: shallow hole blasting of peach-shaped bottom pillars in the construction area stope - medium and deep hole blasting of partition walls in the construction area - deep hole blasting of surrounding rocks in the construction area.

5. The method for mining deep thin tungsten ore under complex void group conditions according to any one of claims 1 to 4, characterized in that: During the entire process of mining and cutting construction, mechanical forced ventilation is used, and fresh air flows into the mining working face from the lower plate along the vein transport tunnel, pedestrian equipment shaft, and layered level tunnel; the blasting smoke is discharged from the gaps in the ore pile, flows back to the upper and middle sections of the return air tunnel, and then discharged to the return air shaft.

6. The method for mining deep thin tungsten ore under complex void group conditions according to any one of claims 1 to 4, characterized in that: Before blasting in step S4, stress gauges or wooden slide gauges are arranged in the rock of the stope surrounding rock and the rock of the pillar tunnel to monitor the ground pressure in the mining area to guide safe mining in the stope.

7. The method for mining deep thin tungsten ore under complex void group conditions according to any one of claims 1 to 4, characterized in that: After each blast in step S4, the ore output is controlled at 30-40% of the collapsed ore volume to provide compensation space for the next mine room collapse; after all the ore in the mine room has collapsed, the ore is evenly discharged at one time.

8. The method for mining deep thin tungsten ore under complex void group conditions according to any one of claims 1 to 4, characterized in that: When mining in the stope, the sections with large, concentrated and complex stress in the same middle section are mined first, and the sections with small stress are mined later; between the middle sections, the upper middle section is mined first, and the lower middle section is mined later.

Images